I found out why I was waking every night after three hours ...
Hi All,
I thought I'd share this experience in case it helps someone. I hope I am sharing in the right place, as I have never posted before.
Recently, and all of a sudden, I was waking up EVERY night between 1.5 hours and 3 hours and then basically had poor sleep for the rest of the night. This went on for about a month, with very few nights being 'normal'. This was having a devastating impact on my well-being and ability to function.
I went to the doctor and was prescribed melatonin, with no result. My blood tests were normal. Basically the doctor had no idea, so I actually thought I'd never be able to function effectively again. I bit dramatic, perhaps, but I was sleep deprived...
Anyway, I have been using CPAP therapy (Resmed Airsense 10) for the last three years and it has been wonderful. I hadn't touched the settings and assumed that everything was fine as my machine wasn't reporting any problems - my AHI and 95% pressure were both unchanged. It made no sense that it was CPAP related, but I also believed that everything is caused by something, so I kept digging.
I decided to have a look at the actual CPAP graphs from data recorded on my machine's SD card using wonderful free software called OSCAR. I was able to look at the pressure graphs before and after the problem initiated. Soon the problem was clear - the minimum pressure was too low - I had never changed it from the default 4 cm H20. This meant that I was getting hit with OSA events in quick succession and that was too much for my arousal threshold. In other words, I could stay asleep with one OSA event, but not for two in quick succession. I changed the minimum pressure to 7.6 cm H20 and that did the trick. The number of OSA events did not change much but now they were spread out.
Why the change anyway? I think I had developed some silent reflux (aka LPR reflux) and that had made my airway more collapsible. Now the CPAP pressure never goes below 7.6 cm H20, and that supports the airway and prevents the double collapse which was waking me up. Recently, I had developed a habit of eating within 3 hours of bedtime and I think that was the cause of the silent reflux. I expect I should be able to be rid of this in time, now that I know what is going on.
Anyway, I hope that helps someone. Everything has a cause. Nothing is random. Sometimes you just have to investigate things for yourself.